I. Field of the Invention
The following description relates generally to wireless communications, and more particularly to providing resource elements for transmission of a reference signal over a channel.
II. Relevant Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and the reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system.
A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, where NS≤min{NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
In addition, mobile terminals can transmit sounding reference signals (SRS) to base stations, which can be utilized, for example, to calculate the uplink channel quality. Base stations can utilize the SRSs in allocating uplink resources to the transmitting mobile terminal. In LTE Release 8 (Rel-8), certain parameters for transmitting SRSs, such as a maximum transmission bandwidth, available subframes, etc. related to a specific cell, can be defined during operation of a wireless network. Furthermore, mobile terminal specific parameters, such as a configuration index of the SRS period and subframe offset for a particular mobile terminal, bandwidth for the terminal, starting resource block, frequency hopping bandwidth, transmission comb, SRS transmission duration, cyclic shift for generating the reference sequence, and/or the like can also be defined at the run time. Mobile terminals in Rel-8 can transmit SRSs as specified by these parameters. LTE-Advanced (LTE-A) mobile terminals can support more advanced technologies and features that can benefit from enhancements to SRS configuration.
There is a need to provide advanced framework for the use of sounding reference signals in LTE-A networks.